WO1996039326A1 - Resistance welding of thermoplastics in aerospace structure - Google Patents
Resistance welding of thermoplastics in aerospace structure Download PDFInfo
- Publication number
- WO1996039326A1 WO1996039326A1 PCT/US1996/003806 US9603806W WO9639326A1 WO 1996039326 A1 WO1996039326 A1 WO 1996039326A1 US 9603806 W US9603806 W US 9603806W WO 9639326 A1 WO9639326 A1 WO 9639326A1
- Authority
- WO
- WIPO (PCT)
- Prior art keywords
- susceptor
- web
- rib
- spar
- lap joint
- Prior art date
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Classifications
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B64—AIRCRAFT; AVIATION; COSMONAUTICS
- B64C—AEROPLANES; HELICOPTERS
- B64C3/00—Wings
- B64C3/18—Spars; Ribs; Stringers
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
- B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
- B29C65/00—Joining or sealing of preformed parts, e.g. welding of plastics materials; Apparatus therefor
- B29C65/02—Joining or sealing of preformed parts, e.g. welding of plastics materials; Apparatus therefor by heating, with or without pressure
- B29C65/34—Joining or sealing of preformed parts, e.g. welding of plastics materials; Apparatus therefor by heating, with or without pressure using heated elements which remain in the joint, e.g. "verlorenes Schweisselement"
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
- B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
- B29C65/00—Joining or sealing of preformed parts, e.g. welding of plastics materials; Apparatus therefor
- B29C65/02—Joining or sealing of preformed parts, e.g. welding of plastics materials; Apparatus therefor by heating, with or without pressure
- B29C65/34—Joining or sealing of preformed parts, e.g. welding of plastics materials; Apparatus therefor by heating, with or without pressure using heated elements which remain in the joint, e.g. "verlorenes Schweisselement"
- B29C65/36—Joining or sealing of preformed parts, e.g. welding of plastics materials; Apparatus therefor by heating, with or without pressure using heated elements which remain in the joint, e.g. "verlorenes Schweisselement" heated by induction
- B29C65/3604—Joining or sealing of preformed parts, e.g. welding of plastics materials; Apparatus therefor by heating, with or without pressure using heated elements which remain in the joint, e.g. "verlorenes Schweisselement" heated by induction characterised by the type of elements heated by induction which remain in the joint
- B29C65/3644—Joining or sealing of preformed parts, e.g. welding of plastics materials; Apparatus therefor by heating, with or without pressure using heated elements which remain in the joint, e.g. "verlorenes Schweisselement" heated by induction characterised by the type of elements heated by induction which remain in the joint being a ribbon, band or strip
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
- B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
- B29C66/00—General aspects of processes or apparatus for joining preformed parts
- B29C66/70—General aspects of processes or apparatus for joining preformed parts characterised by the composition, physical properties or the structure of the material of the parts to be joined; Joining with non-plastics material
- B29C66/72—General aspects of processes or apparatus for joining preformed parts characterised by the composition, physical properties or the structure of the material of the parts to be joined; Joining with non-plastics material characterised by the structure of the material of the parts to be joined
- B29C66/721—Fibre-reinforced materials
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
- B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
- B29C66/00—General aspects of processes or apparatus for joining preformed parts
- B29C66/90—Measuring or controlling the joining process
- B29C66/91—Measuring or controlling the joining process by measuring or controlling the temperature, the heat or the thermal flux
- B29C66/914—Measuring or controlling the joining process by measuring or controlling the temperature, the heat or the thermal flux by controlling or regulating the temperature, the heat or the thermal flux
- B29C66/9141—Measuring or controlling the joining process by measuring or controlling the temperature, the heat or the thermal flux by controlling or regulating the temperature, the heat or the thermal flux by controlling or regulating the temperature
- B29C66/91411—Measuring or controlling the joining process by measuring or controlling the temperature, the heat or the thermal flux by controlling or regulating the temperature, the heat or the thermal flux by controlling or regulating the temperature of the parts to be joined, e.g. the joining process taking the temperature of the parts to be joined into account
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
- B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
- B29C66/00—General aspects of processes or apparatus for joining preformed parts
- B29C66/90—Measuring or controlling the joining process
- B29C66/91—Measuring or controlling the joining process by measuring or controlling the temperature, the heat or the thermal flux
- B29C66/914—Measuring or controlling the joining process by measuring or controlling the temperature, the heat or the thermal flux by controlling or regulating the temperature, the heat or the thermal flux
- B29C66/9141—Measuring or controlling the joining process by measuring or controlling the temperature, the heat or the thermal flux by controlling or regulating the temperature, the heat or the thermal flux by controlling or regulating the temperature
- B29C66/91441—Measuring or controlling the joining process by measuring or controlling the temperature, the heat or the thermal flux by controlling or regulating the temperature, the heat or the thermal flux by controlling or regulating the temperature the temperature being non-constant over time
- B29C66/91443—Measuring or controlling the joining process by measuring or controlling the temperature, the heat or the thermal flux by controlling or regulating the temperature, the heat or the thermal flux by controlling or regulating the temperature the temperature being non-constant over time following a temperature-time profile
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
- B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
- B29C66/00—General aspects of processes or apparatus for joining preformed parts
- B29C66/90—Measuring or controlling the joining process
- B29C66/91—Measuring or controlling the joining process by measuring or controlling the temperature, the heat or the thermal flux
- B29C66/914—Measuring or controlling the joining process by measuring or controlling the temperature, the heat or the thermal flux by controlling or regulating the temperature, the heat or the thermal flux
- B29C66/9161—Measuring or controlling the joining process by measuring or controlling the temperature, the heat or the thermal flux by controlling or regulating the temperature, the heat or the thermal flux by controlling or regulating the heat or the thermal flux, i.e. the heat flux
- B29C66/91641—Measuring or controlling the joining process by measuring or controlling the temperature, the heat or the thermal flux by controlling or regulating the temperature, the heat or the thermal flux by controlling or regulating the heat or the thermal flux, i.e. the heat flux the heat or the thermal flux being non-constant over time
- B29C66/91643—Measuring or controlling the joining process by measuring or controlling the temperature, the heat or the thermal flux by controlling or regulating the temperature, the heat or the thermal flux by controlling or regulating the heat or the thermal flux, i.e. the heat flux the heat or the thermal flux being non-constant over time following a heat-time profile
- B29C66/91645—Measuring or controlling the joining process by measuring or controlling the temperature, the heat or the thermal flux by controlling or regulating the temperature, the heat or the thermal flux by controlling or regulating the heat or the thermal flux, i.e. the heat flux the heat or the thermal flux being non-constant over time following a heat-time profile by steps
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
- B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
- B29C66/00—General aspects of processes or apparatus for joining preformed parts
- B29C66/90—Measuring or controlling the joining process
- B29C66/91—Measuring or controlling the joining process by measuring or controlling the temperature, the heat or the thermal flux
- B29C66/914—Measuring or controlling the joining process by measuring or controlling the temperature, the heat or the thermal flux by controlling or regulating the temperature, the heat or the thermal flux
- B29C66/9161—Measuring or controlling the joining process by measuring or controlling the temperature, the heat or the thermal flux by controlling or regulating the temperature, the heat or the thermal flux by controlling or regulating the heat or the thermal flux, i.e. the heat flux
- B29C66/91651—Measuring or controlling the joining process by measuring or controlling the temperature, the heat or the thermal flux by controlling or regulating the temperature, the heat or the thermal flux by controlling or regulating the heat or the thermal flux, i.e. the heat flux by controlling or regulating the heat generated by Joule heating or induction heating
- B29C66/91655—Measuring or controlling the joining process by measuring or controlling the temperature, the heat or the thermal flux by controlling or regulating the temperature, the heat or the thermal flux by controlling or regulating the heat or the thermal flux, i.e. the heat flux by controlling or regulating the heat generated by Joule heating or induction heating by controlling or regulating the current intensity
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
- B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
- B29C66/00—General aspects of processes or apparatus for joining preformed parts
- B29C66/90—Measuring or controlling the joining process
- B29C66/91—Measuring or controlling the joining process by measuring or controlling the temperature, the heat or the thermal flux
- B29C66/919—Measuring or controlling the joining process by measuring or controlling the temperature, the heat or the thermal flux characterised by specific temperature, heat or thermal flux values or ranges
- B29C66/9192—Measuring or controlling the joining process by measuring or controlling the temperature, the heat or the thermal flux characterised by specific temperature, heat or thermal flux values or ranges in explicit relation to another variable, e.g. temperature diagrams
- B29C66/91951—Measuring or controlling the joining process by measuring or controlling the temperature, the heat or the thermal flux characterised by specific temperature, heat or thermal flux values or ranges in explicit relation to another variable, e.g. temperature diagrams in explicit relation to time, e.g. temperature-time diagrams
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
- B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
- B29C65/00—Joining or sealing of preformed parts, e.g. welding of plastics materials; Apparatus therefor
- B29C65/02—Joining or sealing of preformed parts, e.g. welding of plastics materials; Apparatus therefor by heating, with or without pressure
- B29C65/34—Joining or sealing of preformed parts, e.g. welding of plastics materials; Apparatus therefor by heating, with or without pressure using heated elements which remain in the joint, e.g. "verlorenes Schweisselement"
- B29C65/3472—Joining or sealing of preformed parts, e.g. welding of plastics materials; Apparatus therefor by heating, with or without pressure using heated elements which remain in the joint, e.g. "verlorenes Schweisselement" characterised by the composition of the heated elements which remain in the joint
- B29C65/3476—Joining or sealing of preformed parts, e.g. welding of plastics materials; Apparatus therefor by heating, with or without pressure using heated elements which remain in the joint, e.g. "verlorenes Schweisselement" characterised by the composition of the heated elements which remain in the joint being metallic
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
- B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
- B29C65/00—Joining or sealing of preformed parts, e.g. welding of plastics materials; Apparatus therefor
- B29C65/02—Joining or sealing of preformed parts, e.g. welding of plastics materials; Apparatus therefor by heating, with or without pressure
- B29C65/34—Joining or sealing of preformed parts, e.g. welding of plastics materials; Apparatus therefor by heating, with or without pressure using heated elements which remain in the joint, e.g. "verlorenes Schweisselement"
- B29C65/3472—Joining or sealing of preformed parts, e.g. welding of plastics materials; Apparatus therefor by heating, with or without pressure using heated elements which remain in the joint, e.g. "verlorenes Schweisselement" characterised by the composition of the heated elements which remain in the joint
- B29C65/3484—Joining or sealing of preformed parts, e.g. welding of plastics materials; Apparatus therefor by heating, with or without pressure using heated elements which remain in the joint, e.g. "verlorenes Schweisselement" characterised by the composition of the heated elements which remain in the joint being non-metallic
- B29C65/3492—Joining or sealing of preformed parts, e.g. welding of plastics materials; Apparatus therefor by heating, with or without pressure using heated elements which remain in the joint, e.g. "verlorenes Schweisselement" characterised by the composition of the heated elements which remain in the joint being non-metallic being carbon
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
- B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
- B29C65/00—Joining or sealing of preformed parts, e.g. welding of plastics materials; Apparatus therefor
- B29C65/02—Joining or sealing of preformed parts, e.g. welding of plastics materials; Apparatus therefor by heating, with or without pressure
- B29C65/34—Joining or sealing of preformed parts, e.g. welding of plastics materials; Apparatus therefor by heating, with or without pressure using heated elements which remain in the joint, e.g. "verlorenes Schweisselement"
- B29C65/36—Joining or sealing of preformed parts, e.g. welding of plastics materials; Apparatus therefor by heating, with or without pressure using heated elements which remain in the joint, e.g. "verlorenes Schweisselement" heated by induction
- B29C65/3672—Joining or sealing of preformed parts, e.g. welding of plastics materials; Apparatus therefor by heating, with or without pressure using heated elements which remain in the joint, e.g. "verlorenes Schweisselement" heated by induction characterised by the composition of the elements heated by induction which remain in the joint
- B29C65/3676—Joining or sealing of preformed parts, e.g. welding of plastics materials; Apparatus therefor by heating, with or without pressure using heated elements which remain in the joint, e.g. "verlorenes Schweisselement" heated by induction characterised by the composition of the elements heated by induction which remain in the joint being metallic
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
- B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
- B29C66/00—General aspects of processes or apparatus for joining preformed parts
- B29C66/70—General aspects of processes or apparatus for joining preformed parts characterised by the composition, physical properties or the structure of the material of the parts to be joined; Joining with non-plastics material
- B29C66/71—General aspects of processes or apparatus for joining preformed parts characterised by the composition, physical properties or the structure of the material of the parts to be joined; Joining with non-plastics material characterised by the composition of the plastics material of the parts to be joined
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
- B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
- B29C66/00—General aspects of processes or apparatus for joining preformed parts
- B29C66/70—General aspects of processes or apparatus for joining preformed parts characterised by the composition, physical properties or the structure of the material of the parts to be joined; Joining with non-plastics material
- B29C66/73—General aspects of processes or apparatus for joining preformed parts characterised by the composition, physical properties or the structure of the material of the parts to be joined; Joining with non-plastics material characterised by the intensive physical properties of the material of the parts to be joined, by the optical properties of the material of the parts to be joined, by the extensive physical properties of the parts to be joined, by the state of the material of the parts to be joined or by the material of the parts to be joined being a thermoplastic or a thermoset
- B29C66/739—General aspects of processes or apparatus for joining preformed parts characterised by the composition, physical properties or the structure of the material of the parts to be joined; Joining with non-plastics material characterised by the intensive physical properties of the material of the parts to be joined, by the optical properties of the material of the parts to be joined, by the extensive physical properties of the parts to be joined, by the state of the material of the parts to be joined or by the material of the parts to be joined being a thermoplastic or a thermoset characterised by the material of the parts to be joined being a thermoplastic or a thermoset
- B29C66/7392—General aspects of processes or apparatus for joining preformed parts characterised by the composition, physical properties or the structure of the material of the parts to be joined; Joining with non-plastics material characterised by the intensive physical properties of the material of the parts to be joined, by the optical properties of the material of the parts to be joined, by the extensive physical properties of the parts to be joined, by the state of the material of the parts to be joined or by the material of the parts to be joined being a thermoplastic or a thermoset characterised by the material of the parts to be joined being a thermoplastic or a thermoset characterised by the material of at least one of the parts being a thermoplastic
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
- B29K—INDEXING SCHEME ASSOCIATED WITH SUBCLASSES B29B, B29C OR B29D, RELATING TO MOULDING MATERIALS OR TO MATERIALS FOR MOULDS, REINFORCEMENTS, FILLERS OR PREFORMED PARTS, e.g. INSERTS
- B29K2105/00—Condition, form or state of moulded material or of the material to be shaped
- B29K2105/06—Condition, form or state of moulded material or of the material to be shaped containing reinforcements, fillers or inserts
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
- B29L—INDEXING SCHEME ASSOCIATED WITH SUBCLASS B29C, RELATING TO PARTICULAR ARTICLES
- B29L2031/00—Other particular articles
- B29L2031/001—Profiled members, e.g. beams, sections
- B29L2031/003—Profiled members, e.g. beams, sections having a profiled transverse cross-section
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
- B29L—INDEXING SCHEME ASSOCIATED WITH SUBCLASS B29C, RELATING TO PARTICULAR ARTICLES
- B29L2031/00—Other particular articles
- B29L2031/30—Vehicles, e.g. ships or aircraft, or body parts thereof
- B29L2031/3076—Aircrafts
- B29L2031/3085—Wings
Definitions
- U.S. Application 08/341,779 filed November 18, 1994; which was a continuation-in-part application based upon U.S. Patent Application 08/169,655, filed December 16, 1993; which was a continuation-in-part application of U.S. Patent Application 07/777,739, filed October 15, 1991.
- U.S. Patent Application 08/341,779 also was a continuation-in-part application based upon U.S. Patent Application 08/092,050, filed July 15, 1993; which was a divisional of U.S. Patent Application 07/681,004, filed April 5, 1991, now U.S. Patent No. 5,229,562; and finally, was a continuation-in-part application based upon U.S. Patent Application 08/151,433, filed November 12, 1993. We incorporate these applications and patent by reference.
- the present invention relates to resistance welding of thermoplastic resin composites, especially for lap joints to connect rib and spar webs in a composite wingbox.
- Fiber-reinforced organic resin matrix composites have a high strength-to- weight ratio or a high stiff ness-to- weight ratio and desirable fatigue characteristics that make them increasingly popular as a replacement for metal in aerospace applications where weight, strength, or fatigue is critical.
- Organic resin composites be they thermoplastics or thermosets, are expensive today. Improved manufacturing processes would reduce touch labor and forming time.
- Prepregs combine continuous, woven, or chopped reinforcing fibers with an uncured, matrix resin, and usually comprise fiber sheets with a thin film of the matrix.
- Sheets of prepreg generally are placed (laid-up) by hand or with fiber placement machines directly upon a tool or die having a forming surface contoured to the desired shape of the completed part or are laid-up in a flat sheet which is then draped and formed over the tool or die to the contour of the tool. Then the resin in the prepreg lay up is consolidated (i.e. pressed to remove any air, gas, or vapor) and cured (i.e., chemically converted to its final form usually through chain-extension) in a vacuum bag process in an autoclave (i.e., a pressure oven) to complete the part.
- the tools or dies for composite processing typically are formed to close dimensional tolerances.
- An autoclave has similar limitations; it is a batch operation.
- the prepreg is laid-up to create a preform, which is bagged (if necessary), and placed between matched metal tools that include forming surfaces to define the internal, external, or both mold lines of the completed part.
- the tools and composite preform are placed within a press and then the tools, press, and preform are heated.
- the tooling in autoclave or hot press fabrication is a significant heat sink that consumes substantial energy. Furthermore, the tooling takes significant time to heat the composite material to its consolidation temperature and, after curing the composite, to cool to a temperature at which it is safe to remove the finished composite part.
- the dies or tooling for induction processing are ceramic because a ceramic is not susceptible to induction heating and, preferably, is a thermal insulator (i.e., a relatively poor conductor of heat).
- Cast ceramic tooling is strengthened and reinforced internally, with fiberglass rods or other appropriate reinforcements and externally with metal or other durable strongbacks to permit it to withstand the temperatures and pressures necessary to form, to consolidate, or otherwise to process the composite materials or metals.
- Cast ceramic tools cost less to fabricate than metal tools of comparable size and have less thermal mass than metal tooling, because they are unaffected by the induction field. Because the ceramic tooling is not susceptible to induction heating, it is possible to embed induction heating elements in the ceramic tooling and to heat the composite or metal retort without significantly heating the tools.
- the induction heating elements themselves connect to form a water cooling network. Thus, induction heating can reduce the time required and energy consumed to fabricate a part.
- thermoplastic organic matrix composite preform of PEEK or ULTEM for example, within a metal susceptor envelope (i.e., retort).
- retort metal susceptor envelope
- the susceptor facesheets of the retort are inductively heated to heat the preform.
- consolidation and forming pressure to consolidate and, if applicable, to form the preform at its curing temperature.
- the sealed susceptor sheets form a pressure zone.
- the retort is placed in an induction heating press on the forming surfaces of dies having the desired shape of the molded composite part. After the retort (and preform) are inductively heated to the desired elevated temperature, we apply differential pressure (while maintaining the vacuum in the pressure zone around the preform) across the retort which functions as a diaphragm in the press to form the preform against the die into the desired shape of the completed composite panel.
- the retort often includes three susceptor sheets sealed around their periphery to define two pressure zones.
- the first pressure zone surrounds the composite panel/preform or metal workpiece and is evacuated and maintained under vacuum.
- the second pressure zone is pressurized (i.e., flooded with gas) at the appropriate time and rate to help form the composite panel or workpiece.
- the shared wall of the three layer sandwich that defines the two pressure zones acts as a diaphragm in this situation.
- thermoplastic welding which eliminates fasteners, features the ability to join thermoplastic composite components at high speeds with minimum touch labor and little, if any, pretreatments.
- the welding interlayer (comprising the susceptor and surrounding thermoplastic resin either coating the susceptor or sandwiching it) also can simultaneously take the place of shims required in mechanical fastening.
- composite welding holds promise to be an affordable joining process.
- thermoplastic and thermoset composite parts together, the resin that the susceptor melts functions as a hot melt adhesive. If fully realized, the thermoplastic-thermoset bonding will further reduce the cost of composite assembly.
- U.S. Patent 4,673,450 describes a method to spot weld graphite fiber reinforced PEEK composites using a pair of electrodes After roughening the surfaces of the prefabricated PEEK composites in the region of the bond, Burke placed a PEEK adhesive ply along the bond line, applied a pressure of about 50- 100 psi through the electrodes, and heated the embedded graphite fibers by applying a voltage in the range of 20-40 volts at 30-40 amps for approximately 5-10 seconds with the electrodes. Access to both sides of the assembly is required in this process which limits its application.
- Thermoplastic welding is a process for forming a fusion bond between two faying thermoplastic faces of two parts.
- a fusion bond is created when the thermoplastic on the surface of the two thermoplastic composite parts is heated to the melting or softening point and the two surfaces are brought into contact, so that the molten thermoplastic mixes, and the surfaces are held in contact while the thermoplastic cools below the softening temperature.
- the difficulty is in getting the proper amount of heat to the bondline without overheating the entire structure, and also in achieving intimate contact of the faying surfaces of the two parts at the bondline during heating and cooling despite the normal imperfections in the flatness of composite parts, thermal expansion of the thermoplastic during heating to the softening or melting temperature, flow of the thermoplastic out of the bondline under pressure (i.e., squeeze out), and then contraction of the thermoplastic in the bondline during cooling.
- a susceptor of significantly higher conductivity than the fibers to peak the heating selectively at the bondline.
- An electromagnetic induction coil heats a susceptor to melt and cure a thermoplastic resin (also sometimes referred to as an adhesive) to bond the elements of the assembly together.
- the current density in the susceptor may be higher at the edges of the susceptor than in the center because of the nonlinearity of the coil, such as occurs when using a cup core induction coil like that described in U.S. Patent 5,313,037. Overheating the edges of the assembly can result in underheating the center, either condition leading to inferior welds because of non-uniform curing. It is necessary to have an open or mesh pattern in the susceptor embedded at the bondline to allow the resin to create the fusion bond between the composite elements of the assembly when the resin heats and melts. ⁇ . Moving coil welding processes In U.S. Patent Application 08/286,360, we described a tailored susceptor for approaching the desired temperature uniformity.
- This susceptor designed for use with the cup coil of U.S. Patent 5,313,037, relied upon carefully controlling the geometry of openings in the susceptor (both their orientation and their spacing) to distribute the heat evenly.
- a tailored susceptor having openings with a length (L) to width (W) ratio of 2:1 has a longitudinal conductivity about four times the transverse conductivity.
- we altered the current density in regions near the edges by increasing the foil density (i.e., the absolute amount of metal).
- Increasing the foil density along the edge of the susceptor increases the conductivity along the edge and reduces the current density and the edge heating.
- We increased foil density by folding the susceptor to form edge strips of double thickness or by compressing openings near the edge of an otherwise uniform susceptor. We found these susceptors difficult to reproduce reliably. Also, their use forced careful placement and alignment to achieve the desired effect.
- the tailored susceptor was designed to use with the cup coil of U.S. Patent 5,313,037, where the magnetic field is strongest near the edges because the central pole creates a null at the center. Therefore, the tailored susceptor was designed to counter the higher field at the edges by accommodating the induced current near the edges. The high longitudinal conductivity encouraged induced currents to flow longitudinally.
- Our selvaged susceptor for thermoplastic welding which is described in
- U.S. Patent Application 08/314,027 controls the current density pattern during eddy current heating by an induction coil to provide substantially uniform heating to a composite assembly and to insure the strength and integrity of the weld in the completed part.
- This susceptor is particularly desirable for welding ribs between prior welded spars using an asymmetric induction coil (described in U.S. Patent Application 08/349,647, which we incorporate by reference), because, with that coil, it provides a controllable area of intense, uniform heating, a trailing region with essentially no heating, and a leading region with minor preheating.
- the heating achieved directly corresponds to the power (or power density).
- the resulting susceptor has a center portion with a regular pattern of opening and solid foil edges, which we refer to as selvage edge strips.
- the susceptor in a thermoplastic resin to make a susceptor/resin tape that is easy to handle and to use in performing the composite pieces prior to welding.
- the impedance of the central portion should be anisotropic with a lower transverse impedance than the longitudinal impedance.
- the L/W ratio of diamond shaped openings should be less than or equal to one.
- L for the selvaged susceptor should be less than W.
- thermoplastic welding process described in U.S. Patent Application 08/367,546 enables a moving coil welding process to produce continuous or nearly continuous fusion bonds over the full area of the bondline to yield very high strength welds reliably, repeatably and with consistent quality.
- This process produces improved low cost, high strength composite assemblies of large scale parts fusion bonded together with consistent quality, and uses a schedule of heat application that maintains the overall temperature of the structure within the limit in which it retains its high strength, so it requires no internal tooling to support the structure against sagging which otherwise could occur above the high strength temperature limit.
- the process also produces nearly complete bondline area fusion on standard production composite material parts having the usual surface imperfections and deviations from perfect flatness, while eliminating fasteners and the expense of drilling holes, inspecting the holes and the fasteners, inspecting the fasteners after installation, sealing between the parts and around the fastener and the holes; reducing mismatch of materials; and eliminating arcing from the fasteners.
- an induction heating work coil is passed multiple times over a bondline while applying pressure in the region of the coil to the components to be welded, and maintaining the pressure until the resin hardens.
- the resin at the bondline is heated to the softening or melting temperature with each pass of the induction work coil and pressure is exerted to flow the softened/melted resin in the bondline and reduce the thickness of the bondline while improving the intimacy of the faying surface contact with each pass to militate for complete continuity of bond.
- the total time at the softened or melted condition of the thermoplastic in the faying surfaces is sufficient to attain deep interdiffusion of the polymer chains in the materials of the two faying surfaces throughout the entire length and area of the bondline, thereby producing a bondline of improved strength and integrity in the completed part, but the total time of the faying surfaces at softened temperature is in separate time segments which allows time for the heat in the interface to dissipate without raising the temperature of the entire structure to the degree at which it loses its strength and begins to sag, so the desired shape and size of the final assembly is maintained.
- a structural susceptor allows us to include fiber reinforcement within the weld resin to alleviate residual tensile strain otherwise present in an unreinforced weld.
- the susceptor includes alternating layers of thin film thermoplastic resin sheets and fiber reinforcement (usually woven fiberglass fiber) sandwiching the conventional metal susceptor that is embedded in the resin. While the number of total plies in this structural susceptor is usually not critical, we prefer to use at least two plies of fiber reinforcement on each side of the susceptor. This structural susceptor is described in greater detail in our U.S Patent Application
- the structural susceptor permits gap filling between the welded composite laminates which tailors the thickness (number of plies) in the structural susceptor to fill the gaps, thereby eliminating costly profilometry of the faying surfaces and the inherent associated problem of resin depletion at the faying surfaces caused by machining the surfaces to have complementary contours.
- Standard manufacturing tolerances produce gaps as large as 0.120 inch, which is too wide to create a quality weld using the conventional susceptors.
- the fixed coil process Another advantage with the fixed coil process is that welding can occur using the same tooling and processing equipment that we use to consolidate the skin, thereby greatly reducing tooling costs.
- the fixed coil heats the entire bondline at one time to eliminate the need for skins that are currently used with the moving coil. We can control the temperature and protect against overheating by using our "smart" susceptors as a retort or as the bondline susceptor material or both.
- the present invention is a method for forming structural lap joints between a tab on the spar web and the rib web generally heating a susceptor along the bondline using a voltage source to generate currents in the susceptor.
- Figure 1 is a perspective view of a typical wingbox having resistance welded web lap joints.
- Figure 2 is a schematic detail of a typical rib-spar web lap joint.
- Figure 2A is a detailed schematic of the joint of Figure 2.
- Figure 3 is a plan view of a typical multistrip susceptor.
- Figure 4 is a graph showing a typical hearing cycle for forming an acceptable lap joint.
- Figure 5 is a schematic detailed sectional view of a tensile joint. Detailed Description of a Preferred Embodiment
- a typical composite wingbox 100 designed for assembly without fasteners includes a plurality of longitudinal spars 102 with transverse ribs 104 interspersed along the run of the spars.
- the ribs 104 and spars 102 are joined at rib-spar web lap joints 106, which are schematically illustrated in Fig. 2.
- Each lap joint involves a tab 108 fabricated into the web of the spar and a tongue 110 at the end of the rib web.
- the cap of the rib is cut back at each joint so that the rib web can slide between the spar caps.
- the overlap between the tab and tongue defines the bondline where we position a multistrip susceptor 112 to form a weld or adhesive bond between the spar and rib webs by applying a suitable voltage across the bondline.
- the multistrip susceptor 112 includes a metal foil of the type shown in Fig. 3.
- the foil includes two or more parallel strips 114 that extend the full length of the strip.
- the foil is usually about 0.007 inch thick and each strip is about 0.10 - 0.20 inch wide.
- the strips are separated by gaps of comparable width or slightly - wider dimension which we etch or ablate from a solid foil.
- transverse spacer strips 116 to retain the carrier strips 114 apart.
- the foil is encased within a thermoplastic resin, and might also include fiber reinforcement either of the nature we described in U.S. Patent Application 08/471,625 entitled A Structural Susceptor for Thermoplastic Welding or U.S. Patent Application 08/469,986 entitled A Reinforced Susceptor for Induction
- SUBSTWH SHEET (RULE 26) Welding of Thermoplastic Composites, which we incorporate by reference. Fiber reinforcement alleviates residual tensile strain in the bondline. Tabs on the multistrip susceptor extend outside the bondline to allow connection with the current source. Each strip provides a low impedance longitudinal current path. The arrangement permits uniform heating in the bondline, and the resulting welds have the strength and other physical properties of our induction welds.
- Rib-spar web lap joints 106 are good candidates for resistance welding because these vertical welds often are buried within the structure where it is difficult to create a uniform magnetic field. Resistance welds are also preferred because the welds we produce are comparable to those we create with induction at the spar cap-wingskin and rib cap-wingskin interface and are able to replace mechanical fasteners.
- the rib-spar web lap joints 106 are made before the spar cap-wingskin and rib cap-wingskin welds, so these welds are accessible from the top and bottom. We reach the joints with pressure jaws to hold the spar-susceptor-rib assemblies together with 100-200 psi pressure during the welding process, and this pressure helps us to obtain a high quality bond.
- a conventional arc welding power supply is a suitable current source.
- Upon reaching the maximum temperature we can hold the temperature for a short time (5-10 sec) or can immediately to begin cooling the weld at a rate of about 10-50° F/sec (preferably, 2.5° F/min.). Cool down, therefore, takes about 1.5-5.0 min.
- the ribs and spars might also be green, c-stage, or fully cured thermosets.
- the bond in such case is an adhesive bond rather than a fusion bond.
Landscapes
- Engineering & Computer Science (AREA)
- Mechanical Engineering (AREA)
- Physics & Mathematics (AREA)
- Thermal Sciences (AREA)
- Aviation & Aerospace Engineering (AREA)
- Lining Or Joining Of Plastics Or The Like (AREA)
Abstract
Description
Claims
Priority Applications (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
EP96909794A EP0830283A1 (en) | 1995-06-06 | 1996-03-19 | Resistance welding of thermoplastics in aerospace structure |
AU53178/96A AU5317896A (en) | 1995-06-06 | 1996-03-19 | Resistance welding of thermoplastics in aerospace structure |
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US08/470,168 US7126096B1 (en) | 1991-04-05 | 1995-06-06 | Resistance welding of thermoplastics in aerospace structure |
US08/470,168 | 1995-06-06 |
Publications (1)
Publication Number | Publication Date |
---|---|
WO1996039326A1 true WO1996039326A1 (en) | 1996-12-12 |
Family
ID=23866545
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
PCT/US1996/003806 WO1996039326A1 (en) | 1995-06-06 | 1996-03-19 | Resistance welding of thermoplastics in aerospace structure |
Country Status (3)
Country | Link |
---|---|
EP (1) | EP0830283A1 (en) |
AU (1) | AU5317896A (en) |
WO (1) | WO1996039326A1 (en) |
Cited By (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
EP3800126A1 (en) * | 2019-10-04 | 2021-04-07 | Rohr, Inc. | Cowl door latch assembly |
US11396153B2 (en) | 2018-12-03 | 2022-07-26 | Alliance For Sustainable Energy, Llc | Methods for thermal welding of wind turbine blades |
US11413828B2 (en) | 2017-05-22 | 2022-08-16 | Ratier-Figeac Sas | Aircraft blade and methods of forming and repairing an aircraft blade |
Citations (13)
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BE452317A (en) * | ||||
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US2378801A (en) * | 1941-08-28 | 1945-06-19 | Outboard Marine & Mfg Co | Method and product of joining preformed plastic members |
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DE1756444A1 (en) * | 1968-05-22 | 1970-04-02 | Ver Flugtechnische Werke | Hollow body, in particular an aircraft fuselage with frames distributed along its length and a shell made in a sandwich construction |
GB1315373A (en) * | 1970-04-07 | 1973-05-02 | Ex Press Plastics Ltd | Joining plastics components |
GB2168643A (en) * | 1984-12-10 | 1986-06-25 | Smith H R | Shaping sheet material |
FR2591681A1 (en) * | 1985-12-16 | 1987-06-19 | Lippis Mario | Hydrorib |
US4783228A (en) * | 1986-07-03 | 1988-11-08 | Lockheed Corporation | Method of bonding metal skins to internal support structures |
EP0529917A1 (en) * | 1991-08-23 | 1993-03-03 | British Aerospace Public Limited Company | Fusion bonded thermoplastic leading edge for aircraft aerodynamic surfaces |
WO1993019926A1 (en) * | 1992-03-30 | 1993-10-14 | United Technologies Corporation | Heating means for thermoplastic bonding |
JPH05286496A (en) * | 1992-04-08 | 1993-11-02 | Honda Motor Co Ltd | Wing structure |
WO1994019173A2 (en) * | 1993-02-26 | 1994-09-01 | Raychem Corporation | Methods and devices for joining articles |
-
1996
- 1996-03-19 AU AU53178/96A patent/AU5317896A/en not_active Abandoned
- 1996-03-19 EP EP96909794A patent/EP0830283A1/en not_active Withdrawn
- 1996-03-19 WO PCT/US1996/003806 patent/WO1996039326A1/en not_active Application Discontinuation
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BE452317A (en) * | ||||
FR585195A (en) * | 1923-10-30 | 1925-02-23 | Electrical process for joining materials using fusible binders | |
US2378801A (en) * | 1941-08-28 | 1945-06-19 | Outboard Marine & Mfg Co | Method and product of joining preformed plastic members |
US2715598A (en) * | 1952-12-16 | 1955-08-16 | Bristol Aeroplane Co Ltd | Methods of jointing surfaces by heathardening resins |
DE1756444A1 (en) * | 1968-05-22 | 1970-04-02 | Ver Flugtechnische Werke | Hollow body, in particular an aircraft fuselage with frames distributed along its length and a shell made in a sandwich construction |
GB1315373A (en) * | 1970-04-07 | 1973-05-02 | Ex Press Plastics Ltd | Joining plastics components |
GB2168643A (en) * | 1984-12-10 | 1986-06-25 | Smith H R | Shaping sheet material |
FR2591681A1 (en) * | 1985-12-16 | 1987-06-19 | Lippis Mario | Hydrorib |
US4783228A (en) * | 1986-07-03 | 1988-11-08 | Lockheed Corporation | Method of bonding metal skins to internal support structures |
EP0529917A1 (en) * | 1991-08-23 | 1993-03-03 | British Aerospace Public Limited Company | Fusion bonded thermoplastic leading edge for aircraft aerodynamic surfaces |
WO1993019926A1 (en) * | 1992-03-30 | 1993-10-14 | United Technologies Corporation | Heating means for thermoplastic bonding |
JPH05286496A (en) * | 1992-04-08 | 1993-11-02 | Honda Motor Co Ltd | Wing structure |
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Cited By (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US11413828B2 (en) | 2017-05-22 | 2022-08-16 | Ratier-Figeac Sas | Aircraft blade and methods of forming and repairing an aircraft blade |
US11396153B2 (en) | 2018-12-03 | 2022-07-26 | Alliance For Sustainable Energy, Llc | Methods for thermal welding of wind turbine blades |
EP3800126A1 (en) * | 2019-10-04 | 2021-04-07 | Rohr, Inc. | Cowl door latch assembly |
US11447260B2 (en) | 2019-10-04 | 2022-09-20 | Rohr, Inc. | Cowl door latch assembly |
Also Published As
Publication number | Publication date |
---|---|
AU5317896A (en) | 1996-12-24 |
EP0830283A1 (en) | 1998-03-25 |
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